The Iowa Department of Natural Resources (IDNR) is holding a public hearing at 1:00 p.m. on December 18 at the Muscatine County Conservation Board's Environmental Learning Center to receive comments on the second draft of the state implementation plan (SIP) for fine particular matter (PM2.5) in Muscatine.  The second draft SIP includes updates based on the first round of public comments.  An electronic copy of the revised SIP document, and a copy of IDNR's responses to the comments received on the first draft of the SIP document, may be viewed at www.iowacleanair.com.  All comments on the proposed SIP revisions are due by 4:30 p.m. on December 20, 2013.  Written comments should be mailed to Jim McGraw, Department of Natural Resources, Air Quality Bureau, 7900 Hickman Road, Suite 1, Windsor Heights, Iowa, 50324.  Comments can also be faxed (515) 725-9501 or emailed to Jim.Mcgraw@dnr.iowa.gov.